Fun-kart with two powered wheels

ABSTRACT

A vehicle for leisure or competitive use has a chassis  50  supporting two wheels  12  on a common axis  14  which can be independently driven by respective battery-powered electric motors  22  or internal-combustion engines or be independently kept stationary. Two laterally-spaced castor wheels  18  are disposed in one plane at a longer distance on one side of the axis, and are mounted on the chassis by independent resilient suspension means  52, 54, 56, 58, 60  and  62 . Two laterally-spaced castor wheels  20  are disposed in another plane, which is inclined to that plane in which the castor wheels  18  are disposed, at a shorter distance on the other side of the axis, and are mounted directly on the chassis. The vehicle is provided with a seat  32  and the disposition of the seat and the batteries relative to the axis is so arranged that there is insufficient weight on the castor wheels  18  to resist the torque exerted at the wheels  12  during sudden acceleration as a result of which the vehicle will perform a so-called “wheely” whereby it rears up until the castor wheels  20  contact the ground as shown in broken lines. The vehicle can also be caused to turn rapidly in tight circles by appropriate independent control of the motors or engines. Remotely-controlled toy vehicles can employ the same principle of operation as the fun-karts described for carrying occupants.

[0001] This invention relates to a vehicle which is primarily designed as a fun-kart for leisure or competitive use, but which may also be a remotely-controlled toy.

[0002] There are various kinds of fun-karts already in existence which approximate to miniature motor-cars. They usually have four, or occasionally three, wheels which normally remain in contact with the ground, and the occupant's disposition relative to the plane of the ground does not change. They are usually steered by operating a steering wheel or handle-bar arrangement to turn the front wheel or wheels.

[0003] There are also in existence electric wheel-chairs for the disabled having two wheels on a common axis which can be independently power-driven or kept stationary under the control of a joy-stick for the purpose of steering, and two castor wheels disposed not far in front of said axis. Such wheel-chairs sometimes have elevating and/or reclineable seats, but the driveable wheels and the castor wheels are intended to remain in contact with the ground whilst, in order to prevent these wheel-chairs from accidentally overturning rearwardly, they usually have stabiliser means in the form of two small non-castoring wheels disposed behind said axis a short distance above ground level. Another known design of electric wheel-chair for the disabled has two wheels on a common axis which can be independently power-driven or kept stationary under the control of a joy-stick for the purpose of steering, and two castor wheels disposed not far behind said axis, no stabiliser means being provided.

[0004] Remotely-controlled toy vehicles are also well known.

[0005] The object of the present invention is to provide a novel kind of vehicle in which its disposition, and that of its occupant unless it is a toy, is deliberately variable relative to the plane of the ground whilst exhibiting rapid turning and a higher degree of manoeuvreability than a conventionally steered vehicle. To this end, it utilises some of the features of electric wheel-chairs in a very considerably modified form.

[0006] According to one aspect of the invention, a vehicle comprises a chassis having mounted thereon two laterally-spaced independently power-driven and braked wheels rotateable about a common axis, front stabiliser means spaced in front of said axis, rear stabiliser means spaced behind said axis and, with the vehicle on a horizontal plane with the front stabiliser means and the power-driven wheels on said plane, the rear stabiliser means having a support surface which is disposed above said plane, the centre of gravity of the loaded vehicle, with the vehicle operating on the horizontal plane, being disposed between a first vertical plane containing said axis and a second vertical plane parallel to said first plane and containing the point of contact between the front stabiliser means and the horizontal plane, said vehicle being configured such that the driving force applied on the horizontal plane to the power-driven wheels multiplied by the radius of said wheels is capable of reducing to zero the weight supported at the point of contact between the front stabiliser means and the horizontal plane, and such that further increases in the driving force cause the vehicle to rotate about said axis until the rear stabiliser means contact the horizontal plane.

[0007] Preferably, the chassis is provided with a seat so disposed that the centre of gravity of the vehicle and an occupant of the seat in combination is adjacent to and in front of the first vertical plane.

[0008] Preferably, also, control means for the power-driven wheels are located within reach of the seat.

[0009] The front stabiliser means preferably consist of at least one castor wheel.

[0010] Preferably, the front and rear stabiliser means each consist of two laterally-spaced stabilisers in order to reduce the possibility of the vehicle tipping sideways.

[0011] The front stabiliser means are preferably disposed at a longer distance than the rear stabiliser means from said axis.

[0012] Preferably, the power-driven wheels are driven by at least one internal combustion engine.

[0013] According to another aspect of the invention, a vehicle comprises a chassis having mounted thereon two laterally-spaced independently power-driven and braked wheels rotateable about a common axis, front stabiliser means spaced in front of said axis, rear stabiliser means spaced behind said axis and, with the vehicle on a horizontal plane with the front stabiliser means and the power-driven wheels on said plane, the rear stabiliser means having a support surface which is disposed above said plane, the centre of gravity of the loaded vehicle, with the vehicle operating on the horizontal plane, being disposed between a first vertical plane containing said axis and a second vertical plane parallel to said first plane and containing the point of contact between the front stabiliser means and the horizontal plane, said vehicle being configured such that the maximum driving force applied on the horizontal plane to the power-driven wheels multiplied by the radius of said wheels is at least equal to the weight of the loaded vehicle multiplied by the horizontal distance of the centre of gravity of the loaded vehicle from said axis to enable the loading on the front stabiliser means to be controllably reduced to zero, and such that further increases in the driving force cause the vehicle to rotate about said axis until the rear stabiliser means contact the horizontal plane.

[0014] According to a further aspect of the invention, a vehicle comprises a chassis having mounted thereon two laterally-spaced independently power-driven and braked wheels rotateable about a common axis, front stabiliser means spaced in front of said axis, rear stabiliser means spaced behind said axis and, with the vehicle on a horizontal plane with the front stabiliser means and the power-driven wheels on said plane, the rear stabiliser means having a support surface which is disposed above said plane, the centre of gravity of the loaded vehicle, with the vehicle operating on the horizontal plane, being disposed between a first vertical plane containing said axis and a second vertical plane parallel to said first plane and containing the point of contact between the front stabiliser means and the horizontal plane, said vehicle being configured such that the maximum driving force applied on the horizontal plane to the power-driven wheels multiplied by the radius of said wheels plus the inertia force multiplied by the vertical distance of the centre of gravity of the vehicle above said axis is at least equal to the rolling resistance of the vehicle multiplied by the radius of said wheels plus the weight of the vehicle multiplied by the horizontal distance of the centre of gravity of the vehicle in front of said axis so as to enable the loading on the front stabiliser means to be controllably reduced to zero, and such that further increases in the driving force cause the vehicle to rotate about said axis until the rear stabiliser means contact the horizontal plane.

[0015] The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings of which:

[0016]FIG. 1 is a plan view of one specific embodiment of a fun-kart;

[0017]FIG. 2 is a side elevation of said one embodiment shown in full lines with front castor wheels in contact with the ground and in broken lines with rear castor wheels in contact with the ground;

[0018]FIG. 3 is a plan view corresponding to FIG. 1 of another specific embodiment of a fun-kart; and

[0019]FIG. 4 is a side elevation corresponding to FIG. 2 of said other embodiment.

[0020] Referring now to FIGS. 1 and 2 of the drawings, one specific embodiment of a fun-kart includes a chassis comprising a short rear portion 10 which supports two wheels 12 on a common axis 14, and a longer front portion 16 of a tubular space-frame type connected to the rear portion 10 by hinge means (not shown) adjacent and parallel to said axis and disposed a short distance on the front side thereof. The chassis portions 10 and 16 are urged apart by resilient means (not shown) thus providing a shock-absorbing suspension system for the fun-kart. Stabiliser means comprising two castor wheels 18 supported towards the front end of the chassis portion 16 are disposed in one plane at a longer distance on the front side of the axis 14, and stabiliser means comprising two castor wheels 20 supported at the rear end of the rear chassis portion 10 are disposed in another plane inclined to said one plane at a shorter distance on the rear side of said axis. In other words, with the vehicle on a horizontal plane which represents level ground, a support surface of the rear stabiliser means is disposed above said plane with the front stabiliser means and the power-driven wheels 12 on said plane. The wheels 12 can be independently power-driven in either direction of rotation or kept stationary by respective electric motors 22 of permanent magnet twenty-four-volt direct current type connected to the wheels by respective worm-and-wormwheel speed reduction gearboxes 24 and powered by two twelve-volt batteries 26, said motors and gearboxes being of any suitable conventional state of the art kind. The motors 22 provide regenerative braking. The motors 22, gearboxes 24 and batteries 26 are supported by the rear chassis portion 10, and the distance of the batteries to the rear of the axis 14 is variable to enable the balance, that is to say the weight distribution, of the fun-kart to be adjusted having regard to the weight of the occupants hereinafter referred to. The speed and regenerative braking of the wheels 12 are controlled by a twin-channel controller 28 of the type employed in electric wheel-chairs, which enables the fun-kart to be steered and controlled rapidly and precisely by a single joy-stick 30. A main occupant's seat 32 with a back-rest 34 and a head restraint 36 is secured at the rear of the front chassis portion 16, and said portion has an integral roll-bar 38 to protect the main occupant if the fun-kart should overturn. However, this is unlikely as the seat 32 is disposed very close to the ground in order to provide stability when cornering. The seat 32 is also disposed just forward of the axis 14 so that the weight of the main occupant, partially counterbalanced by the batteries 26, normally holds the front castor wheels 18 in contact with the ground. The centre of gravity of the loaded vehicle, with the vehicle operating on the horizontal plane, is disposed between a first vertical plane containing the axis 14 and a second vertical plane parallel to said first plane and containing the point of contact between the front stabiliser means and the horizontal plane. A secondary occupant's seat 40 is provided near the front end of the front chassis portion 16 above the castor wheels 18. The disposition of the seat 32 and/or the seat 40 relative to the axis 14 may be variable to assist in adjusting the balance of the fun-kart. The controller 28 is secured to one side of the front chassis portion 16 so that the joy-stick 30 is located within reach of the seats 32 and 40. At the front end of the front chassis portion 16 there is fitted a pneumatic-tyred wheel freely rotateable about an axis 44 which is substantially vertical when the front castor wheels are in contact with the ground. The wheel 42 is not intended to make any contact with the ground, being provided to deflect the fun-kart safely away from walls and the like, to guide the kart around corners on a track, and to act as a shock-absorbing bumper in the event of a head-on collision.

[0021] Referring now to FIGS. 3 and 4 of the drawings, another specific embodiment of a fun-kart is in most respects similar to the embodiment of FIGS. 1 and 2, and like parts are identified by the same reference numerals. One difference is that a one-piece chassis 50 is employed, each of the two castor wheels 18 being mounted on the chassis 50 by independent resilient suspension means shown in FIG. 4. One of said means is disposed at each side of the chassis 50 and comprises an arm 52 which is pivoted at its rear end at a point 54 on the chassis 50 and carries one of the castor wheels 18 at its front end, and a telescopic strut 56 which is urged into extended condition by a helical compression spring 58 and is connected between a point 60 on the chassis 50 and an intermediate point 62 on the arm 52. Another difference is that the wheels 12 are controlled by independent speed controllers and associated electronic twist grips 64 best seen in FIG. 3 which are located within reach of the seats 32 and 40. The twist grips 64 can control both the direction of rotation and the speed of the motors 22, or alternatively they control only the speed and a manually-operated switch is provided to reverse said motors.

[0022] In the operation of both specific embodiments hereinbefore described, a single occupant can use either of the seats 32 and 40, or two occupants can use both of said seats. When a single occupant uses the main seat 32, or two occupants include a light-weight person such as a child using the secondary seat 40, and the dispositions of the seats 32 and 40 and the batteries 26 relative to the axis 14 are adjusted as necessary to keep the front stabiliser means resting lightly on the horizontal plane when the kart is stationary, the driving force applied on the horizontal plane to the power-driven wheels 12 multiplied by the radius of said wheels is capable of being increased to reduce to zero the weight supported at the point of contact between the front stabiliser means and the horizontal plane, further increases in the driving force causing the vehicle to rotate about the axis 14 so that the kart rears up until the rear stabiliser means contact the horizontal plane as shown in broken lines in FIG. 2 so as dramatically to change the longitudinal inclination, and also in the case of the seat 40 the height, of the occupant or occupants relative to the ground. More explicitly, the kart is able to rear up as just described when the driving force applied on the horizontal plane to the power-driven wheels 12 multiplied by the radius of said wheels is at least equal to the weight of the loaded vehicle multiplied by the horizontal distance of the centre of gravity of the loaded vehicle from the axis 14 to enable the loading on the front stabiliser means to be controllably reduced to zero, further increases in the driving force causing the vehicle to rotate about the axis 14 until the rear stabiliser means contact the horizontal plane. Deceleration will cause the kart to fall back onto its front castor wheels 18. The weight distribution characteristics of the fun-kart are such that up to 100 percent of its weight can be concentrated over the power-driven wheels 12, affording it far better traction than any conventional two-wheel-driven vehicle. Regardless of whether it is stablised on its front or rear castor wheels, or even balanced on the wheels 12 alone, the fun-kart can be caused to turn in progressively tighter circles by slowing, stopping or, where suitable provision is made, reversing either one of the motors 22. An occupant of the seat 40 will then experience a feeling of being centrifuged. Where suitable provision is made, the fun-kart can also be driven and turned in reverse by appropriate control of the motors 22, but “wheelies” are not then possible. Acceleration, deceleration, turning and reversing can all be controlled from either of the seats 32 and 40, but the controls will of course feel to be reversed for an occupant of seat 40. The fun-kart can be used for leisure or for competitive racing, and is well adapted for use on very undulating terrain.

[0023] Numerous modifications are possible within the scope of this invention. The secondary seat 40 can be omitted. The relative positions of the batteries 26 and the main seat 32 can be reversed when the secondary seat 40 is provided, in which case the arrangement of the seats can be such that occupants of both seats can experience a “wheely” and the feeling of being centrifuged. A three-seat configuration can also be provided, with one seat in the middle and one seat at each end. The two electric motors 22 can be replaced by two internal-combustion engines of any suitable conventional, state of the art kind, especially two-stroke engines which can desirably rotate at very high speeds, together with associated clutch/brake means or by a single electric motor or a single internal-combustion engine in conjunction with suitable means for independently driving and braking the wheels 12. The joy-stick or the twist grips can be replaced by other control means such as a steering wheel, foot pedals, and hand levers. The speed reduction gearboxes can be of other than worm gear type, and can be replaced by belt and/or chain speed reduction means. The fun-kart can be designed so as to be readily dismantled, either to facilitate its transportation or to allow its drive means to operate other attachments. As well as adjustable batteries and seat or seats, ballast weights can be used to balance the fun-kart for different numbers and weights of occupants and or to maximise the inherent ability of the fun-kart to negotiate very undulating terrain. Such ballast weights can be adjustable in position, and this can be effected by motorised means while the fun-kart is in motion. The height of the rear castor wheels 20 above the ground when the front castor wheels 18 are in contact with the ground can be adjustable to vary the angle to which the fun-kart rears up when a “wheely” is performed. The rear castor wheels can incorporate resilient suspension means as well as or instead of the front castor wheels. Instead of providing a suspension hinge adjacent to the axis 14, it can be provided adjacent to the front castor wheels 18. If desired, there need be no suspension means at all. A single castor wheel disposed on the longitudinal centre-line of the fun-kart can be employed at the front and/or at the rear, with a corresponding reduction in cornering ability. Stabiliser means in the form of skids can take the place of the front and rear castor wheels when the fun-kart is used on sand, snow or other soft or slippery surfaces. The fun-kart can be small in size for a child, or large and very powerful for more than one adult. A remotely-controlled toy vehicle can employ the same principle of operation as the fun-kart.

[0024] In another modification, the fun-kart can be designed so that the centre of gravity of the loaded vehicle is located at an appreciable height above the axis 14, by seating the occupant at an appreciable height or possibly by making provision for him to stand. This will increase the magnitude of the sensations he will experience. In this case the inertia force acting horizontally on the vehicle at the centre of gravity becomes much more significant by virtue of the height of the centre of gravity, and must be taken into account in designing the kart to render it capable of performing a “wheely”. Thus the maximum driving force applied on the horizontal plane to the power-driven wheels 12 multiplied by the radius of said wheels plus the inertia force multiplied by the vertical distance of the centre of gravity of the vehicle above the axis 14 when said centre is so located must be at least equal to the rolling resistance of the vehicle multiplied by the radius of said wheels plus the weight of the vehicle multiplied by the horizontal distance of the centre of gravity of the vehicle in front of the axis 14 so as to enable the loading on the front stabiliser means to be controllably reduced to zero, further increases in the driving force causing the vehicle to rotate about the axis 14 until the rear stabiliser means contact the horizontal plane. The rolling resistance is normally not significant and has therefore been ignored hitherto, but has been included in the preceding sentence to provide a more complete explanation of the dynamics to which the vehicle is subjected. 

1. A vehicle comprising a chassis having mounted thereon two laterally-spaced independently power-driven and braked wheels rotateable about a common axis, front stabiliser means spaced in front of said axis, rear stabiliser means spaced behind said axis and, with the vehicle on a horizontal plane with the front stabiliser means and the power-driven wheels on said plane, the rear stabiliser means having a support surface which is disposed above said plane, the centre of gravity of the loaded vehicle, with the vehicle operating on the horizontal plane, being disposed between a first vertical plane containing said axis and a second vertical plane parallel to said first plane and containing the point of contact between the front stabiliser means and the horizontal plane, said vehicle being configured such that the driving force applied on the horizontal plane to the power-driven wheels multiplied by the radius of said wheels is capable of reducing to zero the weight supported at the point of contact between the front stabiliser means and the horizontal plane, and such that further increases in the driving force cause the vehicle to rotate about said axis until the rear stabiliser means contact the horizontal plane.
 2. A vehicle according to claim 1 , wherein the chassis is provided with a seat so disposed that the centre of gravity of the vehicle and an occupant of the seat in combination is adjacent to and in front of the first vertical plane.
 3. A vehicle according to claim 2 , wherein control means for the power-driven wheels are located within reach of the seat.
 4. A vehicle according to claim 1 , wherein the front stabiliser means consist of at least one castor wheel.
 5. A vehicle according to claim 1 , wherein the front and rear stabiliser means each consist of two laterally-spaced stabilisers in order to reduce the possibility of the vehicle tipping sideways.
 6. A vehicle according to claim 1 , wherein the front stabiliser means are disposed at a longer distance than the rear stabiliser means from said axis.
 7. A vehicle according to claim 1 , wherein the power-driven wheels are driven by at least one internal combustion engine.
 8. A vehicle comprising a chassis having mounted thereon two laterally-spaced independently power-driven and braked wheels rotateable about a common axis, front stabiliser means spaced in front of said axis, rear stabiliser means spaced behind said axis and, with the vehicle on a horizontal plane with the front stabiliser means and the power-driven wheels on said plane, the rear stabiliser means having a support surface which is disposed above said plane, the centre of gravity of the loaded vehicle, with the vehicle operating on the horizontal plane, being disposed between a first vertical plane containing said axis and a second vertical plane parallel to said first plane and containing the point of contact between the front stabiliser means and the horizontal plane, said vehicle being configured such that the maximum driving force applied on the horizontal plane to the power-driven wheels multiplied by the radius of said wheels is at least equal to the weight of the loaded vehicle multiplied by the horizontal distance of the centre of gravity of the loaded vehicle from said axis to enable the loading on the front stabiliser means to be controllably reduced to zero, and such that further increases in the driving force cause the vehicle to rotate about said axis until the rear stabiliser means contact the horizontal plane.
 9. A vehicle comprising a chassis having mounted thereon two laterally-spaced independently power-driven and braked wheels rotateable about a common axis, front stabiliser means spaced in front of said axis, rear stabiliser means spaced behind said axis and, with the vehicle on a horizontal plane with the front stabiliser means and the power-driven wheels on said plane, the rear stabiliser means having a support surface which is disposed above said plane, the centre of gravity of the loaded vehicle, with the vehicle operating on the horizontal plane, being disposed between a first vertical plane containing said axis and a second vertical plane parallel to said first plane and containing the point of contact between the front stabiliser means and the horizontal plane, said vehicle being configured such that the maximum driving force applied on the horizontal plane to the power-driven wheels multiplied by the radius of said wheels plus the inertia force multiplied by the vertical distance of the centre of gravity of the vehicle above said axis when said centre is so located is at least equal to the rolling resistance of the vehicle multiplied by the radius of said wheels plus the weight of the vehicle multiplied by the horizontal distance of the centre of gravity of the vehicle in front of said axis so as to enable the loading on the front stabiliser means to be controllably reduced to zero, and such that further increases in the driving force cause the vehicle to rotate about said axis until the rear stabiliser means contact the horizontal plane. 